The present invention relates generally to an imaging apparatus and fuser components thereof for use in electrostatographic, including digital, contact electrostatic printing, and like apparatuses. The fuser components, including fuser members, pressure member, donor members, external heat member, and the like, are useful for many purposes including, in the case of a fuser member, fixing a toner image to a copy substrate. More specifically, the present invention relates to fuser components comprising a platinum catalyzed addition cured silicone layer. In embodiments, the silicone layer is positioned on a substrate, which may be of many configurations including a roller, belt, film, or like substrate. In other embodiments, the silicone rubber layer has an outer layer thereon. In embodiments, there is positioned between the substrate and the silicone layer, and/or between the silicone layer and the outer layer, an intermediate and/or adhesive layer. The present invention may be useful as tuser members in xerographic machines, including color machines.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
The use of thermal energy for fixing toner images onto a support member is well known and methods include providing the application of heat and pressure substantially concurrently by various means, a roll pair maintained in pressure contact, a belt member in pressure contact with a roll, a belt member in pressure contact with a heater, and the like. Heat may be applied by heating one or both of the rolls, plate members, or belt members. With a fixing apparatus using a thin film in pressure contact with a heater, the electric power consumption is small, and the warming-up period is significantly reduced or eliminated.
It is important in the fusing process that minimal or no offset of the toner particles from the support to the fuser member take place during normal operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there. The referred to “hot offset” occurs when the temperature of the toner is increased to a point where the toner particles liquefy and a splitting of the molten toner takes place during the fusing operation with a portion remaining on the fuser member. The hot offset temperature or degradation of the hot offset temperature is a measure of the release property of the fuser, and accordingly it is desired to provide a fusing surface, which has a low surface energy to provide the necessary release. To ensure and maintain good release properties of the fuser, it has become customary to apply release agents to the fuser roll during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils to prevent toner offset.
Another important method for reducing offset, is to impart antistatic and/or field assisted toner transfer properties to the fuser. However, to control the electrical conductivity of the release layer, the conformability and low surface energy properties of the release layer are often affected.
U.S. Pat. No. 4,711,818 teaches a fuser member having as a layer, a crosslinked product of a mixture of at least one polyfluoroorganosiloxane, filler, heat stabilizer, crosslinking agent and crosslinking catalyst.
U.S. Pat. No. 4,659,621 teaches a one-layer platinum catalyzed addition cured silicone layer as a coating on a donor roller for an electrostatographic machine.
U.S. Pat. No. 4,763,158 teaches a fuser member having as a layer, a platinum catalyzed addition cured silicone material.
U.S. Pat. No. 4,777,087 teaches a platinum catalyzed addition cured polyorganosiloxane useful as layers in a fuser member for an electrostatographic apparatus.
U.S. Pat. No. 4,868,251 teaches an ultraviolet light absorbing silicone composition. A platinum catalyzed vinyl/hydride addition cured silicone material can be used in crosslinking. The silicone material can be used in lenses.
U.S. Pat. No. 4,925,895 teaches a polyorganosiloxane platinum catalyzed addition curable silicone elastomer useful as a layer for a fuser member useful in xerographic machines.
U.S. Pat. No. 4,983,641 teaches a platinum-catalyzed addition cured silicone foamable composition.
U.S. Pat. No. 5,082,871 teaches a platinum catalyzed addition curable polyorganosiloxane release coating composition.
U.S. Pat. No. 5,164,462 teaches an ultraviolet light absorbing silicone elastomer that is crosslinked using a platinum-catalyzed addition cured silicone material. The silicone materials may be useful in lenses.
U.S. Pat. No. 5,217,837 teaches a peroxide cured silicone elastomer layer for a fuser member.
U.S. Pat. No. 5,352,753 teaches an ultraviolet light absorbing silicone layer with filler. The silicone may be formed with a crosslinking agent that is a platinum catalyzed addition cured silicone. An amino siloxane is disclosed as a crosslinking agent. The coating is useful as a lens material.
U.S. Pat. No. 5,401,570 teaches a fuser member comprising a substrate and thereover, a silicone rubber containing a filler. The silicone elastomer can be peroxide cured.
U.S. Pat. No. 5,464,896 teaches an addition cured silicone layer with fluorocarbon outer surface as coatings for fuser members.
U.S. Pat. No. 5,466,768 teaches an ultraviolet light absorbing silicone layer with filler. The silicone may be formed with a crosslinking agent that is a platinum catalyzed addition cured silicone. An amino siloxane is disclosed as a crosslinking agent. The coating is useful as a lens material.
U.S. Pat. No. 5,474,821 teaches a fuser member having a layer of platinum catalyzed addition cured silicone material.
Known fuser coatings include high temperature polymers such as polytetrafluoroethylene, perfluoroalkoxy, fluorinated ethylene propylene, silicone rubber, fluorosilicone rubber, fluoroelastomers, and the like. These coatings have been found to have adequate release properties and control toner offset sufficiently. However, problems have resulted with known fuser member layers, including that the fuser member prematurely hardens resulting in a life short fall. Some known fuser members have also been shown to show a susceptibility to contamination, scratching and other damage. Further, silicone rubber layers tend to swell upon application of release agents. Moreover, fuser members have been shown to provide toner offset or inferior release capability, which allows for inappropriate copies and/or prints, and toner contamination to other parts of the machine.
In order to solve some of the above problems, a boron nitride filler has been introduced into a silicone rubber to provide a superior layer material. However, use of boron nitride is expensive and has been found not to solve: all the above problems.
A platinum catalyzed addition cured silicone layer as a layer for fuser members has been shown to correct some, if not all, of the above problems. For example, the layer improves delivery and processability. However, the layer is not thermally conductive or thermally stable.
Therefore, a need remains for fuser components for use in electrostatographic machines that have superior mechanical properties, including the ability to maintain superior heat age stability, and consequently, improved life short fall. A further need remains for fuser coatings having increased toughness and increased tensile strength, having a reduced susceptibility to contamination, scratching, and other damage. In addition, a need remains for a fuser component with a decreased tendency to swell in the presence of release agents. A need further remains for a fuser member layer, which decreases toner offset, resulting in a decrease or elimination of inferior prints and/or copies and toner contamination to other parts of the machine. In addition, a need remains for a fuser member having superior thermal conductivity, good conformability, lower modulus, and lower hardness. Further, it is desired to dispense with the need for expensive fillers such as boron nitride in the fuser layer(s).